Apparatus for manufacturing a steering wheel pad

ABSTRACT

An apparatus for manufacturing an injection molded steering wheel pad having a cover and a pocket formed between a first projection and a second hook-shaped projection, that together hold an arm of an air bag device. The apparatus includes fixed and movable mold members opposed to one another. The movable mold member moves along a predetermined moving path to selectively contact and separate from the fixed mold member. Core members are provided in one of the mold members for forming the first and second projections in the pad. The core members are movable between retracted and extended positions with respect to one of the movable and fixed mold members so that the formed pad projections can be separated from the mold by varying movements of the core members, relative to each other and the mold in which they operate.

This is a continuation of application Ser. No. 08/721,627, filed Sep.26, 1996, which is a division of application Ser. No. 08/405,022 filedMar. 16, 1995 and now U.S. Pat. No. 5,603,968.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for manufacturing asteering wheel pad and a method for manufacturing therefor.

2. Description Of Related Art

Steering wheels with pads for accommodating air bags are widely used.Such pads are injection molded, using a resin material, into aconfiguration enabling the accommodation of air bags therein.

More particularly, as shown in FIG. 10, a known steering wheel pad body32 includes a pocket 35a for securing a metal fitting 42 of an air bagdevice generally indicated at 43. The pocket 35a is defined between afirst upper projection 34 and a hook-shaped second lower projection 35both extending inwardly from the inner wall of the pad body 32.

A conventional mold 36, described with reference to FIGS. 8 and 9, isutilized to manufacture the conventional steering wheel pad 31 havingtwo projections 34 and 35, which differ from each other in shape. Themold 36 comprises a fixed mold half 37, a movable mold half 38 whichmoves relative to mold half 37, and a pushing core 39 extensible along amoving path of mold half 38. The core 39 has a first protrusion 39a, asecond protrusion 39b, and a depression "D" between the two protrusions39a, 39b to form the two projections 34, 35 and the pocket 35a on thepad body 32.

For manufacturing the pad 31, a cavity 40 is first defined by moving themovable mold half 38, with the core 39 disposed therein, to a positionclose to the fixed mold half 37. Molten resin is then injected into thecavity 40 to thereby form the pad 31. Afterwards, the mold half 38 andthe core 39 are separated from the mold 37. Subsequently, the pad 31 isseparated from the mold half 37.

As shown in FIG. 9, the core 39 is separated from the mold half 38 topush the pad 31 out from the mold half 38. A lateral force is thenapplied to a bottom portion 33 of the body 32 by an operator's hand 41.This lateral force resiliently bends the bottom portion 33 to separatethe second and first projections 35, 34 from the associated protrusions39b, 39a, respectively, and thus permits the pad 31 to be separated fromthe core 39.

However, the above-described operation requires the operator torepeatedly apply force to bend the pad body 32 when removing the pad 31from the core 39. This makes the manufacturing operation tiresome forthe operator.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a steering wheelpad manufacturing apparatus and a simplified method for manufacturing asteering wheel pad, compared to those of the prior art, as discussedabove.

To achieve the above objective, an apparatus for manufacturing asteering wheel pad is provided. The pad is formed by resin injectionmolding so as to have a cover and a pocket portion defined between afirst projection and a second hook-shaped projection. The pocket portionholds an arm of an air bag device accommodated in the pad.

The apparatus has a first and second mold portions, such as a fixed moldhalf and a movable mold half which opposes the fixed mold half. Themovable mold half is adapted to move along a predetermined path toselectively contact and separate from the fixed mold half. The apparatusfurther has a plurality of core members which are movable betweenretracted and extended positions with respect to one of the movable andfixed mold halves. The core members define a molding cavity along withthe movable and fixed molds halves, when the core members are in theirretracted position.

In particular, the core members include a first core member, for formingthe first projection of the pad, which is movable along a predeterminedmoving path. At least one second core member and at least one third coremember are also provided, the latter for forming the second projectionof the pad.

According to another aspect of the present invention a method formanufacturing a steering wheel pad is proposed. The pad is formed byinjecting a resin into a cavity to form a cover and a pocket between afirst projection and a second hook-shaped projection for holding an armof an air bag device accommodated in the pad. Then, by selectivelyextending and retracting the core members, the steering wheel pad can beseparated from the mold apparatus without requiring an operator to exertmanual force therefor.

First, the pad is formed by injecting a molten resin into a cavitydefined by a fixed mold half and an opposed movable mold half. One ofthe mold halves includes the first, second and third core members, eachbeing movable between a retracted position and an extended position withrespect to one of the mold halves. Each of the core members is held inits retracted position at this stage.

Second, the movable mold half is moved along a predetermined moving pathto separate it from the fixed mold half while the core members aremaintained in their retracted position. The pad is held on the coremembers and the movable mold half;

Third, the core members are selectively extended and retracted so thatpad becomes disengaged from the mold half and released. To accomplishthis, each of the first and second core members are moved along thepredetermined path, to an extended position and then the third coremembers are moved in a direction obliquely to and intersecting thepredetermined path, whereby the pad is separated from the mold and thesecond projection is separated from the third core member(s);

Fourth, the second and third core members are retracted, during whichtime the second core members are moved in a direction along the movingpath of the moveable mold half, and the first projection of the pad isseparated from the second core member; and

Finally, the first core member is retracted so that the pad is separatedfrom the first core member.

Other objects, features, and characteristics of the present invention,as well as methods of operation and function of the related elements ofstructure, and the combination of parts and economies of manufacture,will become more apparent upon consideration of the following detaileddescription and the appended claims with reference to the accompanyingdrawings, all of which form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention, may best be understood by reference to thefollowing description of the presently preferred embodiments togetherwith the accompanying drawings, in which:

FIG. 1 (a) is a cross-sectional view taken along the line I--I of FIG. 7showing a first step according to the present invention, in which acavity of a mold is filled with molten resin;

FIG. 1 (b) is a cross-sectional view showing the movable mold halfseparated from the fixed mold half;

FIG. 2 is a partial cross-sectional view showing the second step inwhich a second projection of the steering wheel pad is separated from aninclined core member;

FIG. 3 is a partial cross-sectional view showing a third step in which afirst projection of the steering wheel pad is separated from a firstcore member;

FIG. 4 is a partial cross-section view showing a second pushing coremember moved upward from the position shown in FIG. 3;

FIG. 5 is a partial cross-sectional view illustrating a fourth step inwhich a pad is separated from the second core member;

FIG. 6 is a partial cross-sectional view showing a steering wheel withan air bag device therein;

FIG. 7 is a partial plan view showing a movable half mold, two coremembers, and an inclined core member;

FIG. 8 is a partial cross-sectional view illustrating a cavity of aconventional mold filled with molten resin;

FIG. 9 is a partial cross-sectional view showing a pad separated fromthe conventional core member of FIG. 8; and

FIG. 10 is an enlarged partial cross-sectional view of a conventionalmetal fitting for mounting an air bag.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment according to the present invention will now be describedwith reference to the drawings.

FIG. 6 illustrates a portion of a steering wheel 2 with an air bagdevice 30 accommodated therein. The steering wheel 2 has a pad 3. Thepad 3 includes a central cover 4 having an open bottom. The cover 4 hasside walls provided with holding portions 5 integrally formed on theinner side thereof. The holding portions 5 serve to hold the air bagdevice 30 in place and are thicker than cover 4.

Each holding portion 5 includes a first upper projection 6 and a secondhook-shaped lower projection 7, both extending inwardly. A pocket 29 isdefined between the two projections 6, 7. Further, projections 6, 7 aregenerally perpendicular to a predetermined path of a movable mold 15(seen in FIGS. 1(a) and 1(b).

The pad 3 is preferably made from an elastomer, such as a high polymerhaving rubber-like elasticity under normal temperatures. SEBS(styrene-ethylene-butadiene-styrene copolymer), for example can be usedas the elastomer. Accordingly, pad 3 easily deforms under theapplication small stresses and returns quickly to its originalconfiguration when the stress is removed.

The air bag device 30 comprises a main air-bag body 1 and an inflator 11which supplies inflating gas to the air bag body 1. The air bag body 1and the inflator 11 are attached to the holding portion 5 via, forexample, a bag holder 8, a retainer 9, rivets 10, and nuts 12. Moreparticularly, the top end of the bag holder 8 is engagingly insertedinto a pocket 29. The bottom end of the bag holder 8, an open end 1a ofthe air bag body 1, and the retainer 9 are all held on a flange 11a ofthe inflator 11. Legs 9a project downward through the open end 1a of theair bag body. The legs 9a, the bag holder 8, and the flange 11a are eachfastened by nuts 12. The retainer 9, open end 1a, and bag holder 8 arealso secured in sandwiched manner by rivets 10.

To manufacture the above-described pad 3, the molding apparatus 13 shownin FIGS. 1(a), 1(b) and 7 is utilized. The mold apparatus 13 comprises afixed mold half 14, a movable mold half 15, a first core member 16, foursecond core members 17, and four inclining core members 18.

The movable mold half 15 is typically moved vertically by a conventionaldrive mechanism (not shown) connected to the mold half 15. In thisinstance, the movable mold half 15 approaches the fixed mold half 14when moving upward, and is separated there from when moving downward. Onthe upper section of the mold half 15, a number of recesses are providedfor receiving various core members including a recess 19 foraccommodating the first core member 16, four recesses 20 foraccommodating second core members 17, and four recesses 21 foraccommodating inclining core members 18.

The movable mold half 15 also includes rod passages 22, 23 that extendvertically through the mold half 15 and communicate with recesses 19,20. The mold half 15 also includes four rod passages 24, each beinginclined, with respect to the predetermined moving path of the mold half15, at a designated angle θ. Each rod passage communicates with anassociated recess portion 21.

The first core member 16 is fixed to a top of a push rod 25 which isslidably inserted into passage 22. The first core member 16 is providedwith a protrusion 16a. Protrusion 16a extends outwardly and is generallyperpendicular to the predetermined movement path of mold half 15. Thecore member 16 fits into the recess 19 when the core member 16 is in alower, retracted position within mold half 15. Core member 16 isdisposed above the recess 19 when the core member 16 is in a projectedposition outside the mold half 15 as in FIGS. 2-4.

The second core members 17 are fixed to the tops of push rods 26,respectively. Each of the rods 26 are slidably inserted into anassociated rod passage 23. Each core member 17 fits into an associatedrecess 20 when the core member is in a retracted position within themold half 15. The core members 17 will abut against the first coremember 16 when the core member 17 are in a retracted position as in FIG.1(a). The core members 17 project from the recess 20 when they are in aposition outside the mold 15.

The inclined third core members 18 are each fixed to the top of one ofthe inclined push rods 27, respectively. Each push rod 27 is slidablyinserted into an associated rod passage 24. Each third core member 18has a second protrusion 18a. The protrusion 18a is generallyperpendicular to the predetermined movement path of the mold half 15.Each third core member 18 fits in a respective recess 21 when the coremember 18 is in a retracted position within the mold half 15. In theirretracted positions, core members 18 abut against the bottom surface 16bof the first core member 16. Also, each core member 18 is disposed abovethe recess 21 when the core members 18 are in a projected position.Since each rod 27 slides upward at an inclined angle to lift coremembers 18 to the projected position, core members 18 also move inwardlyin a direction oblique to the predetermined movement path of core member16, as shown in FIG. 2.

The lower end portions of rods 25, 27 are connected to each other by aconnecting member C. This connection allows movement of core members 16and 18 to be synchronized while keeping core members 18 abutting againstthe bottom 16b of core member 16.

As shown in FIG. 1(a), a cavity 28 is defined by mold halves 14, 15 whenthe movable mold half 15 closes with the fixed mold half 14 and with allcore members 16, 17, 18 being in their respective retracted positions.

The first projection 6 of pad 3 is formed between the first and secondprotrusions 16a, 18a, respectively. The second projection 7 of pad 3 isformed between second protrusion 18a and a step portion 15a (see FIG. 2)formed on the surface of movable mold half 15.

A method for manufacturing the pad 3, utilizing the above apparatus,will now be explained by the following sequence of steps.

In the first step as illustrated in Figs. 1(a) and 1(b), core members16, 17, 18 begin in their retracted positions and accommodated in theirrespective recesses 19, 20, 21. The movable mold half 15 is then movedupward to engage the fixed mold half 14. When mold half 15 comes intopartial contact with mold half 14, a cavity 28 is defined between themold halves 14, 15 and the core members 16, 17, 18. Molten resin (e.g.,SEBS) is then injected into cavity 28 and cooled, thus forming asteering wheel pad 3 having the desired configuration.

The first projection 6 of pad 3 is formed between the first protrusion16a of first core member 16 and protrusions 18a. The second projection 7is formed between the protrusion 18a of each inclining core member 18and mold 15.

In the second step, the movable mold half 15 and the core members 16,17, 18 are first separated from the fixed mold half 14. This movementcauses pad 3 to be separated from mold half 14 and moved downward,integral with mold half 15 and core members 16, 17, 18.

Then, with reference now to FIG. 2, core members 16, 17, 18 aresimultaneously moved upward from the movable mold half 15. The pad 3 isthereby separated from mold half 15 and the core members 16, 17, 18 areextended from their respective recesses 19, 20, 21. The extended axis ofthe inclined rods 27 intersect the movement path of mold half 15. Thisenables core member 18 to move inwardly in a direction opposite to thedirection of extension of second projection 7. The pad 3 is still heldby core members 16, 17 and is, therefore, constrained from moving.Accordingly, the second protrusion 18a of core member 18 is separatedfrom pocket 29 formed on the interior surface of pad 3.

In the third step, as shown in FIG. 3, the upward movement of the firstand inclining core members 16, 18 is stopped. However, each of thesecond core 17 members continue moving upward. The pad 3, supported bycore members 17, thus moves upwardly along with them.

Although the second projection 7 of the pad 3 was separated from theinclining core members 18, the first projection 6 remains engaged withprotrusion 16a of the first core member 16 during the second step.However, during the third step, the holding portion 5 of the pad isgradually deflected due to its elasticity when the pad 3 is pushedupwardly by second core members 17. Hence, projection 6 is bent awayfrom and separated from protrusion 16a. Afterwards, the holding portion5 returns to its original configuration because of its own resiliency.

In the fourth step, the second core members 17, which support pad 3, aremoved down from the position shown in FIG. 4. During the downwardmovement of core members 17, the simultaneous downward movement of thepad 3 is restricted when holding portion 5 contacts the protrusion 16a.This produces an upward force on that side of pad 3 counter to the forceon the opposite side created by the downward movement of core members17. These opposing forces separate the pad 3 from core members 17. Aftercore member 17 is further retracted, the core members 16 ,17 ,18 movedownward together and again fit into their associated recesses 19, 20,21, as shown in FIG. 5.

Finally, an extracting mechanism (not shown) is separately provided toremove pad from the mold 13.

Although only one embodiment of the present invention has been describedherein, it should be apparent to those skilled in the art that thepresent invention may be embodied in many other specific forms withoutdeparting from the spirit or scope of the invention. Particularly, itshould be understood that the present invention may be embodied in themodes given below.

(1) A different type of a mold half with a movable mold which moveshorizontally may be employed. In this case, the pad may be droppedfreely after being separated from the mold, thus making it possible toomit the extracting mechanism.

(2) In the third step of the above embodiment, only the second coremembers 17 are moved upward after the first and inclining core members16, 18 are stopped. On the other hand, the second core members 17 may bestopped and the remaining core members 16, 18 may be moved downward. Thesignificant feature is that pad 3 is supported by core members 17 whilecore member 16 moves away downwardly from pad 3 thereby establishingcountering separating forces. This can be accomplished by suitablerelative movement between the core members 16, 17.

(3) In the fourth step of the above embodiment, while the core members17 are moving down, the downward movement of the 3 may be regulated byhaving pad 3 contact core member 18, or portions other than theprotrusion 16a, on core member 16.

(4) In the fourth step, core members 16 and 18 could be moved upwardinstead of having core members 17 move downward.

(5) The core members 16, 17, 18 could be retracted and projected fromthe fixed mold half 14 instead of from the movable mold half 15.

While the invention has been described in connection with what ispresently considered to be the most practical and preferableembodiments, it is to be understood that the invention is certainly notlimited to these disclosed embodiments, but, on the contrary, isintended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims.

What is claimed is:
 1. An apparatus for manufacturing an injectionmolded steering wheel pad having a cover and a pocket portion definedbetween a first projection and a second hook-shaped projection thatcooperate to hold an arm of an air bag device, said apparatuscomprising:a fixed mold portion; a movable mold portion opposed to saidfixed mold portion, said movable mold portion being movable along afirst moving path so as to selectively contact and separate from saidfixed mold portion; and a plurality of core members, each core memberbeing movable between respective retracted and extended positions withrespect to one of said movable and fixed mold portions, said pluralityof core members being arranged when in said retracted position, todefine a cavity along with said movable and fixed mold portions, whereinsaid plurality of core members includes a first core member for formingthe first projection in the pad, said first core member being movablealong said moving path of said movable mold portion, at least one secondcore member being movable along said moving path; and at least one thirdcore member adjacent to said first core member for forming the secondprojection in the pad, said third core member being movable relative tosaid first core member along a direction perpendicular to said movingpath.
 2. The apparatus as set forth in claim 1, wherein one of said moldportions is provided with a plurality of recesses, each receiving acorresponding one of said plurality of core members when said one ofsaid plurality of core members is in a respective retracted position. 3.The apparatus as set forth in claim 2, a first rod, at least one secondrod, and at least one third rod, each said rod being coupled to arespective one of said first, second and third core members.
 4. Theapparatus as set forth in claim 3, wherein each of said first, second,and third rods are slidably movable in respective first, second, andthird passages provided in said one of said mold portions including saidplurality of core members.
 5. The apparatus as set forth in claim 4,wherein said third passages are inclined relative to said firstpassages.
 6. The apparatus as set forth in claim 5, wherein said atleast one third core member is adapted to contact said at least onesecond core member such that said at least one third core member canmove in a sliding manner relative to said first core member in adirection generally perpendicular to a direction of movement of saidmovable mold portion.
 7. The apparatus as set forth in claim 6, furthercomprising:a first protrusion formed on and laterally extending fromsaid at least one second core member; a second protrusion formed on andlaterally extending from said at least one third core member; and astepped portion formed on a surface of said one of said mold portionsprovided with said plurality of core members.
 8. The apparatus as setforth in claim 1, wherein two different core members among said first,second, and third core members are adapted to form the pocket portion inthe steering wheel pad during an injection molding process.